1. Technical Field
The present invention relates to a light emitting device and a projector.
2. Related Art
A semiconductor light emitting device such as a semiconductor laser or a super luminescent diode (hereinafter, referred to as an “SLD”) is used as, for example, a light source of a projector. The SLD is a semiconductor light emitting device which has an incoherent property in the same manner as a normal light emitting diode, exhibits a wide-band spectral shape, and can generate an output of several hundreds mW with a single element in the same manner as the semiconductor laser in terms of light output characteristics.
The SLD includes a refractive index waveguide in which a structure for lowering a refractive index is provided on both sides of a region of an active layer into which a current is injected and light is confined in an in-surface direction, and a gain waveguide in which the region of the active layer into which a current is injected is used as a light waveguide as it is without providing the structure for lowering a refractive index. In the refractive index waveguide type, light can be efficiently confined so as to be amplified, and thus it is possible to implement a more highly efficient SLD.
For example, JP-A-2012-43950 discloses a refractive index waveguide SLD having a waveguide which is tilted in a stripe shape.
Light is exponentially amplified toward a light emission surface which emits the light in a light waveguide of the above-described SLD. For this reason, there is a case where gain saturation may occur due to the number of carriers converted into light becoming insufficient in the vicinity of the light emission surface, and thus the output of the SLD may be reduced.